Compendium is a computer program and social science tool that facilitates the mapping and management of ideas and arguments. The software provides a visual environment that allows people to structure and record collaboration as they discuss and work through wicked problems.

The software was released by the not-for-profit Compendium Institute. The current version operationalises the issue-based information system (IBIS), an argumentation mapping structure first developed by Horst Rittel in the 1970s. Compendium adds hypertext functionality and database interoperability to the issue-based notation derived from IBIS.

Compendium source code was fully released under the GNU Lesser General Public License on 13 January 2009. Compendium can still be downloaded, but is no longer actively maintained.

Compendium diagrammatically represents thoughts as nodes displayed as labeled icons—with types such as issues/questions, ideas/answers, arguments, references, and decisions—and represents interconnections between different nodes. It can be used for applications as varied as: issue mapping in meetings, design rationales and requirements analysis, meeting management (agendas and minutes), action item and issue tracking, requirements management, classification, management templates, and reference databases (such as personal knowledge bases).

The software can be used by a group of people in a collaborative manner to document their collective ideas using visual diagrams. A group facilitation method called dialogue mapping is especially suited for use with Compendium.

Compendium templates for critical thinking can be used to create argument maps using the argumentation schemes developed by argumentation theory scholars such as Douglas N. Walton, Chris Reed, and Fabrizio Macagno. Argumentation schemes are pre-defined patterns of reasoning for analysing and constructing arguments; each scheme is accompanied by a list of critical questions that can be used to evaluate whether a particular argument is good or fallacious. By using these argumentation schemes, users of Compendium can examine claims in more detail to uncover their implicit logical substructure and improve the rigor and depth of discussions.

There are ten default types of node: question, answer, list view, map view, pro, con, note, decision, reference, argument. There are three types of relationship between nodes: associative, transclusive, categorical. Images can be placed directly into a view, assigned to a node, or assigned to the background picture. Features of Compendium include:

Users can choose to use Compendium with either the Apache Derby (internal) or MySQL (external) relational database management system.